My math: Boiling a cup (0.24 kg) of water from 25°C to 70°C ~45kJ (0.24kg×45°C×4182J/kg°C) Raising 0.24 kg of water up a height 30,000 m ~ 71kJ (0.24kg × 9.8m/s^2 × 30,000 m)

So my math says raising the temp of a cup of water from room temp would be equivalent to raising it about 19 km high.

Edit: I'm a moron who can't read, boiling water from 25 to 100 °C takes:

0.24 kg × 75 °C × 4182 J/kg°C ~ 75kJ

Now if only we could figure out a way to actually do that without burning a bunch of fuel for the purpose of lifting fuel! Something something tyranny of rockets.

The general formula:

MCT=MGH

So height=(heat capacity of liquid*change in temp)/9.81

In our case (4184*70)/9.81 ~ 30,000 meters