>I'm not patient enough to stick around and make sure it doesn't spill over. The cleanup is not worth it for me.
I had this problem a lot. The solution is to get a deep bowl and/or use the microwave power settings (for instance try 50% for 5 minutes). These are the bowls I use and man I wish I bought them earlier. They work perfectly for 40 grams of oatmeal / 1 cup of water and even fruit.
I also put a plate under the bowl just in case and makes it easier to take out of the microwave.