Heating up food without microwave oven? What is the best way?

I will soon be moving to a place with water heater, but no oven. I do order and store food a lot to keep costs down.

I have Googled but I get a lot of hits with camping gear that I don't need. People are recommending a thermos? Or reheatable boxes?

I'm looking for something I can do with household gear, pots/pans etc.

The best I can think of is some kind of steaming solution that only uses bowls and pots. Perhaps I would need to buy something?

To clarify, this is a rental in Bali. I travel light. I don't want to cook, just reheat meals that I order in