Hmm, my thought is that the reason popcorn pops is because the moisture inside the kernal is heated and expands - creating the explosion (maybe not true, but it is what I have always thought). So in my theory, it would be because the kernals are too dry.
Most of you were on the right track. Apparently, the hull of some of the kernels is weak and once heated developes a small crack. This allows the pressure created by the heating, to escape.
So the kernel never developes the minimum pressure needed to cause it to burst.
I know you'll all sleep better tonight now that you're loaded up with that important info!
Anyone else care to ask a question about something? We could keep this thread going.
I don't think they ever get together and discuss anything because if they did it wouldn't be one year this is great for you and the next year oh don't eat that or use this, nothing ever is as expected. Information will change many times about food, products. medication, weather patterns and everything else that that so call study.