If you eat instant oatmeal that you cook in a microwave you’ve probably experienced the explosion that makes a mess of the inside of the microwave. Here’s why and what to do about it.
Your oatmeal is being heated very quickly. A microwave will cause the water to boil inside its puddle in the bowl as much or more than at the bottom as it would when cooked on a stove. It has to boil and boiling means steam builds up and has to go somewhere. As long as the oatmeal is not gotten to its “Sticky” stage of cooking where it starts to thicken up, the steam can leave the liquid quite easily. However when the oatmeal has cooked to the point of thickening the steam still has to leave but now it’s lifting some or all of the sticky mass it came from. The sticky mass provides some back pressure that holds the steam in….until it doesn’t anymore, and that makes little steam explosions in your oatmeal, and explosions big or small throw chunks of stuff all over the place. In this case it’s inside your microwave.
So what to do about it? Simple, divide the cooking up into phases, stopping between phases to stir the oatmeal. The early phase can run longer until the oatmeal starts to thicken. Then you do shorter runs as it gets thicker and thicker. Because you’re using a microwave there will always be hot spots and dead spots in the food your cooking. Stirring in between mixes the hot oatmeal with cooler oatmeal and brings the temperature below boiling. The subsequent phases bring that temperature up again, but not long enough to build up much steam pressure.
With the typical packet of corporate supplied oatmeal and my 700 watt microwave I give that first phase about 1 minute 45 seconds. I stir, then around 45 seconds, stir, then 30 – 10 seconds on the last phase, depending on how well cooked it is before starting. My oatmeal comes out perfectly each time.
Your oatmeal can come out perfectly too. Just don’t let it “bump”. This applies to any kind of stuff that thickens as it cooks. If you don’t want it to bump you’ll have to watch it to let it cool down a bit before resuming cooking temperature, never letting the internal steam pressure build up.