What would cause a glass pan to explode?

There are oven-proof glass pans like Pyrex and non-oven-proof. Had she baked something in that pan before? Was the oven set at an unusually high temperature? Usually, 400˚ F is the cut-off point.

It sounds as though she chose an unsuitable container.

It was either not an oven-proof pan, was a defective oven-proof pan, or was an oven-proof pan subjected to heat beyond what was recommended.

My guess is similar to @gailcalled . Putting a non-oven proof glass pan from room temperature straight into a very hot oven might cause it to shatter.

I will assuming the glass pan was supposed to be used in the oven.

According to a factory tour of Corning Glass work in Corning NY the process to make the pan is more complex than just pouring melted glass into a mold. The inner and outer parts of the glass have different stress characteristics. Think of it as the outer part being shrink wrapped onto the inner. The outer part is in tension while the inner part is in compression. This makes a very strong product. However, if there is a crack or a scratch in the outer surface the whole unit can let go with amazing force. If the process is poor – like in a cheap knock off the outer coating can be thin and you can get breakage. You might save a buck or two but at what cost.

Drastic change in temperature can do it. Was the food you put it in frozen?

Possible if something got in there that was cold—did she put some water in there? Also, of course as others have said, if the glass was not over-proof. Otherwise, if you take a hot glass pan out of the oven and put in on the counter where there is some water, it can crack.

My oven-proof glass pan that had been used many times in the oven, broke in the oven full of scalloped potatoes one Easter. Just bad luck, I thought.

Overheating. I’ve had glass explode before. its really scary.

The last alternative with which I am familiar has something to do with how the chicken was dispatched. My dad shot a rabbit when we were kids and there was some live fragment of something left in the poor rabbit because when it went, it blew the whole door off the oven (much less what happened to the pan).