I swear that rumor is never going to die. The candle is not really exploding what is happening is the glassware for some reason got too hot and broke, it will sound like a gun going off in your house. Things that can cause a gel candle to "explode" polar FOs, to low a FP on the FOs, To much FO and oil pockets are created when the flame get to the me you get a little bon fire which will cause the glass to gel to hot and break. Items that are not fire resistant in the candle they catch fire. Not crimping above the sand. Sand can become flammable. It will absorb the FO out of your gel wax and than becomes flammable. Improper wicking. That is just a few of the reason why it would happen.