Tempered glass is pretty quirky stuff. It can shatter for seemingly no reason at all (though it's likely that it's a microscopic crack or pit). On the other hand, it can show almost amazing strength.
A good example is from our experience, having purchased brand new windows for our 67 Airstream. These are darned expensive for the side windows because the glass is large and curved. So I installed the new glass, obviously following the wrong advice in doing so. And off we went to Zion National Park, where it was darned hot. We laid down to take an afternoon nap -- and ka-boom! One of the windows simply fell out. Not only did it just fall out, but it fell out and hit one of the large, metal tables seen at sites in national parks. It literally bounced off the table and hit the gravel. Completely unharmed. (The only harm was my psyche, realizing the bad mistake I'd made in mounting the windows with a tar-like tape material.)