I'm American, and I often heat up leftovers with a toaster oven or on the stove. For some foods it gets better results.

There's also steamers. They are especially popular in Asia.

I don't heat up leftovers, I just eat them cold. But we do have a microwave (we bought it at the beginning of the pandemic so we could heat up frozen meals--we didn't have one before). I had cold leftover pasta for lunch today. My wife turns up her nose at cold leftovers but I'm not picky.

Isn’t it problematic to heat water in a microwave?

Its possible to superheat water in a microwave so that it will explosively boil when disturbed, but it is fairly easy to safeguard against, as well.

My microwave has a picture of a cup with a spoon in it, this stops superheating.

How?

It provides a non-smooth surface to induce steam bubbles to form.

I know in chem labs we used to use little chunks of ceramic for test tubes, but those aren't desirable in your tea.

>My microwave has a picture of a cup with a spoon in it, this stops superheating.

This appears to be a microwave setting. I don't see how that would provide a non smooth surface

“My microwave has a picture on it” is what was said; graphic instructions are common.

Ah ok I see now!

Sorry if I was unclear. It's basically this: https://physics.stackexchange.com/questions/234042/should-i-...

Only if you overheat it. Drives all the gas out and makes the water off/flat.