On a recent Seattle morning, Adam Welch heard an crashing sound and saw broken glass everywhere. Turned out that his dining room had table spontaneously shattered...There are a number of useful comments at the thread, particularly this one:
Tempered and heat strengthened glass can explode due to nickel sulfide inclusions, which are basically bits of nickel sulfide in the glass that change state slowly after being heated up during the tempering process. Because tempered glass is strong due to the fact that the outer layers are in compression and the inner in tension (kind of a two dimensional truss structure, when there is a small failure all the stored energy is released rather quickly. Interestingly enough, there was a rather spectacular failure of a large sheet of tempered glass in the dinosaur hall of the Museum of Natural History in NYC about a decade ago. You can actually go through the shattered dice of tempered glass that fails in this way and find the point of failure; it will create two round dice that meet at the point where the inclusion was, these dice are quite different than the rest of the pieces which tend to be square.Another comment reminded me of my own post four years ago - Why do teardrops explode? That post includes two impressive videos of Prince Rupert's drops exploding.
After reading the BoingBoing post and my old one, I searched YouTube for relevant videos and found several. A Massachusetts TV channel reported on exploding patio tables in 2007, and exploding shower doors in 2009 [embedding disabled because by some convoluted logic they want it viewed on YouTube but not on blogs??], but here's one documenting the aftermath of an exploding bathroom vanity:
It's not apparently a predictable event, but the knowledge that it can happen may be useful when making decorating or remodeling decisions.