At my parent’s house, they have an instant hot water dispenser. It’s like any other filtered little water fountain that sits right next to the sink and connects down through the counter into a water line.

I know nothing at all about the science behind it or how it works, but the water comes out literally steaming just one second after I turn it on.

It has two nozzles on top, one that’s room temp, one for the instant hot. It is more than hot enough for tea and is ready in just a few seconds.