Here's a rough datapoint for you. A regular 1500W kitchen kettle will heat a liter of water (15C to 100C) to boiling in about 3 minutes. That's 13.5 A at 120VAC(I specify, because your domestic power conditions may be quite different). So, now we need to know your volume of water for comparison. If, for example, you want to heat 100 ml(10x smaller), and can do it in 9 minutes(3x longer), first approximation says you can apply 50W((1500/10)/3) for 9 minutes and boil your 100 ml. A bit less time will bring the water to 90C.
There are all kinds of approximations in that little example, but it's the sort of back-of-the-envelope calculation that gives you a good idea of what you can expect.
So,
- what's your volume
- what form of power can you use (it might not be appropriate to suggest you use 115VAC, you might be limited to 12VDC for example for safety reasons).
- what heating time is acceptable?
Over to you, @carlos_de_francisco.