My friend Kelly was at my house a while back. We were making macaroni and cheese for the kids. We discussed a pin that we'd seen that says if we place a wooden spoon over a pot of boiling water that the water won't boil over. We tried it and it worked! Just the other day, I did the trick again, but to my dismay, I had a boiled over mess! I did have the burner on full blast though! I say that the wooden spoon helps, but isn't 100% effective! I'll keep using it!
Here's the pin: http://diyhshp.blogspot.com/2011/10/did-you-know.html