Why do people use glass tables?

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Recently, a relative of mine came to me asking me to explain a strange physics phenomenon. She had 3 glass tables; 2 small and one large arranged neatly such that the small tables were half enclosed under the larger one. She recounted to me that one morning she was sitting in a room adjacent to the one with the tables (but one which allowed her a full view of the tables) with nobody else in the house at the time, when all of a sudden and without any prior indication, one of the smaller glass tables exploded. Not simply shattered, but exploded with a loud pop or bang, sending pieces across the room (thankfully no one was nearby to get hit by flying glass shards).

Naturally, I was a bit skeptical and asked if she was exaggerating slightly and if she had pictures of the resulting debris. She did have pictures and she was not exaggerating.

I had a few ideas how this happened off the top of my head, but this is something I've definitely never seen before. She had this table for at least 4 years before it shattered, but I don't think she's had it more than 10. As you can see, the light is shining through the window onto the tables, but judging by the sharpness of the shadows, I'd say it wasn't particularly warm light (likely a partly cloudy day).

Now, I'm aware that thermal stresses can cause glass to fracture or break, but there were apparently no prior indications of problems, the glass did a bit more than simply fracture or break apart, and I am unsure if the environmental conditions were enough to cause that kind of thermal variation. Discussions in the comments seem to have rested on the notion that this is likely safety glass, which has higher internal pre-stresses and can be known to explode when those stresses get too high (there can be multiple causes of this, however, and an ideal answer should explain the most likely, let's say, 2).

So my main question is what would cause the glass table to spontaneously explode?

Potential answerers might want to start on the wikipedia page for Spontaneous glass breakage. However, that was a bit insufficient an explanation for me, so consider being more thorough (math, diagrams, etc is all welcome).

So let's say we find an answer about why this thing broke. From what research I've done, it seems more common for spontaneous breakage to mean spontaneous shattering, not an explosion like this (unless it has a very significant thermal variation that causes high internal pressure, but with another table over top and what looks like less than peak sunlight, I fail to see how that much thermal stress could be applied here. Feel free to correct me though). Thus, my secondary question: Rather than simple fracturing or shattering, why would this cast projectile debris so far? What kind of internal pressure must have built up?

I'm fairly sure I know the reasoning myself, but I'm not entirely certain. It'd be good to get a more sound answer from others. In the meantime, I did tell her to replace all the glass tables, just in case the others had similar defects, and to look for the ones that say "Now with less explosions than ever" as opposed to the ones that say "Start your day off with a bang".

Have you thought about the role your wood furniture plays in the look and feel of your home?  Whether it’s an antique end table, a funky new coffee table or a majestic dining room table - your wood furniture is essentially the statement piece for an entire room.

But keeping that special, conversation starter clean can be quite a daunting task.  Some cleaners can attract dust, while others can leave a greasy film.  And then there’s the issue of preserving the color and detail that makes the piece unique and extraordinary.  It’s enough to make your mind spin. 

Yet, before you throw in the towel on your lump o’ timber, consider a glass tabletop.  A custom cut and sized piece of glass on top of your wood table may just be the answer to your wood woes.  There are actually a lot of benefits to a glass tabletop that you may not have even thought about.

Glass tabletops can be stylish.

The glass tabletop edges can be custom cut to give your tabletop an elegant and sophisticated motif or a fun and trendy vibe.

Glass tabletops can protect against harmful UV rays.

Your skin isn’t the only thing the sun can damage.  Tinted tabletop glass can provide your nice wood furniture with a sunscreen, of sort, that will protect and prevent sun damage.

Glass tabletops can prolong the life of your wood furniture.

Water rings, scratches and even sun damage can age your wood furniture prematurely.   A glass tabletop can protect from daily wear and tear and can help safeguard the characteristics that make the piece special.

Glass tabletops are easy to take care of and keep clean.

All you need is a dry, clean cloth and a spray bottle full of water or glass cleaner to keep your glass squeaky clean and shiny.

And of course, Glass Doctor® can help you with all of your custom glass tabletop needs.  Give your local Glass Doctor a call.  Because, at Glass Doctor…we fix your panes!