I was making french toast this morning and sprayed Pam cooking spray on the pan. I put two pieces of egg soaked bread in my 12" Premium Chefmate pan. The burner was between medium and low, and after about a minute of cooking, the pan started to make a loud popping sound. I grabbed my two year old who was sitting on the counter watching me cook and we ran out of the kitchen. After several more pops, and a big loud one, I peeked back into the kitchen and grabbed the pan off the burner and set it on one of the cool burners and discovered that my pan no longer sits flat on the cooktop. The bottom of the pan bubbled out and I now have a pan that wobbles when I put it down. Does anybody know what may have caused this? I'm not sure if the pan was defective or if I did something wrong. (I'm not the world's most experienced cook.)

Christie