…that little wood binding strips are stronger than a glass jar?

I wanted to darken some 1 mm x 2 mm wood binding strips for a rosette, so I slipped them into a glass jar and put the jar in the microwave. I don’t remember what setting I chose but it didn’t take long before the jar simply burst into so many pieces. If I had taken a moment to think about it, I would have known that was going to happen…

I believe the explanation could be that that the wood that was touching the jar on the inside (or perhaps even pressure caused by the rings expanding inside the jar) caused the glass to expand unevenly. Of course, it could also be  the jar was made of “unsafe” glass that is not suited for the microwave in the first place.