Ask a Physicist: Exploding Coffee

Nick, from the US, wants to know:"After retrieving my medium sized ceramic cup of coffee from the microwave that had been in for 2 minutes, I quickly stirred the coffee with a thick straw. Immediately bubbles started to rise and overfilled the half full cup, unfortunately burning my thumb. Could you please tell me what reactions caused this to happen? Thank you very much."Nick,Sounds like you superheated your coffee! Ordinarily, water boils at 212°F, but under the right conditions, the molecule...