I read this article, http://www.mydesert.com/article/20120604/NEWS0803/206040334/Glass-bottles-may-led-Rancho-Mirage-house-fire, telling how an 84 year old woman who is the coordinator of her community emergency response team (CERT) lost her home to a fire. The fire investigation determined that some of the empty glass bottles she stored to be used to share water with neighbors after an emergency reflected sunlight and burst. When it did it directed fire onto the wood pallets and that was it. Her entire house is gone.
Just a reminder that we as preppers have a lot of stuff. Make sure that it's not going to cause its own disaster.