Frigidaire short behind knobs?

First off sorry if this was covered else where. But have noticed lately a loud popping or short sound coming from my knobs when they are on. Higher the temperature the more I notice It. I have the slightest clue what it is. I’m not sure when or where the stove was purchased, it was with house when I brought it back in October of 2014. Any help would-be greatly appreciated. Any questions feel free to ask. Thanks :slight_smile: