We have a couple of theories, though.
1) It had just rained and then the sun came out. Perhaps the air pressure or temperature changed so fast that the glass simply shattered as it expanded faster than the frame.
2) Aliens came down from Mars and zapped the table with their radar guns. This was for revenge when they abducted me last week and I made a mess of their spaceship.
3) It was John Paul (pictured here). He is a bit mischevious. And he's a law student, too. Enough said.
So, whoever is interested, we've got a free glass table top to whomever would like. We think Waste Management may have already taken it, though.