Why do grapes in a microwave burst into brilliant, violent, white flames? It's plasma, baby! - Reeko's Mad Scientist Lab
Cut a grape in half but leave the skin of one side intact, Place the grape in the microwave and crank up the microwave radiation. Viola, the grape bursts into a brilliant, white-hot flame. The same effect occurs with two grapes in a microwave that touch each other. The flame you see is plasma – a hot mixture of electrons and electrically charged atoms, or ions.