I've boiled coffee before. You do what you must when your machine breaks! I will agree with others that reheated coffee is either bitter (stove, hot plate) or bland (microwave), but I understand and appreciate those who do their best not to waste. My preferred way around this is to drink it chilled with a little cream!
I don't drink coffee in large volume any more, and I blaspheme by drinking exclusively decaf, but I highly recommend a pour over to anyone looking for a good cup. I enjoy the process of making it, it's easy to clean, I don't have any waste, and I can make more if I decide I want more
website. Plus, if I brew concentrated hot over a big cup of ice, I can make a hybrid strong cold brew/iced coffee in minutes that's great for summer.