Pops and sparks from burner/bayou classic kettle

Im wondering if this has happened to anyone else or if someone can explain why it happened. I have a 10 gallon bayou classic kettle with a turkey fryer from Gander Mountain for my HLT, and a 15 gallon bayou classic kettle with a Blichman burner for my boil kettle. Tonight when I was heating water in the HLT all the sudden there was a big pop and sparks from the burner/bottom of the kettle. After that happened it continued to work fine. After I finished the mash and got about 13 gallons of wort boiling the same thing happened with the blichman burner and 15 gallon kettle. This time it actually blew the kettle with 13 gallons of liquid up into the air enough to slide the kettle about 2 inches to one side of the burner. This "explosion" also seems to have messed up my ball lock valve on the 15 gallon kettle because it now leaks out through the valve when it is closed. I thought the first time was some fluke, but then it happened again with a different burner/kettle just 2 hours later. Nothing like this has ever happened to me before. Does anyone have any insight into why this happened?

this happens to me when the burner gets wet, maybe even if the ground is wet below it

Ok, that might make sense. It was raining tonight and I had my setup right at the edge of my garage door. They could have gotten some water on them.