I remember a while ago my father dropped a glass lid and it smashed. It looked something like this. When that happened, for about 5 minutes afterwards, the glass parts were splitting, kind of like popcorn, and you could hear the sound. I was just wondering why this happened, and the particles didn't just sit quietly in their own original parts?
Due to internal stress in the material. This stress might be there due to fabrication technology or due to heat cycling while usage (less likely).
Here is an idea. You could have cracking (fracture) behaving as a critical process. From the dropping of the glass you could have micro-fractures forming. In time and because of the amount of tension (and energy) concentrated in the glass from the fall, these micro-fractures slowly could organize to form big fractures, which would cause the popping sounds you continued to hear for some time after the fall of the glass lid. If it was some kind of crystal that broke I would be more confident that that was the case, but since it is some kind of glass, I am not so sure that it can happen something like that, since glass is amorphous, but I am not sure that it can't either.