Boiling water without burning it

I usually do it in the microwave, but I put the bread in the toaster to toast it first; it somewhat prevents the chewy-rather-than-toasty bread you end up when you zap it. (Also, sometimes I butter the toast before I put the cheese on. If I feel the need for extra grease. Which, sometimes, you just need extra grease.)

ETA: also, since this *is* boilingwater: don't use tinfoil if you're microwaving it. :D Use a plate.