I am pretty sure the pressure alone will not be enough to get water to boil. As someone mentioned, water is incompressible, so putting it under extreme pressure will not do much. We used to test high pressure tube fittings at up to 6000 psi, filled to the top with water, with no noticable change in the temperature. This prevented an potentially deadly explosion, because a if a device was filled with air at that pressure, the expansion of the air would cause a huge BOOM! and probably kill anyone nearby. Filled with water though, it's more of just a small harmless pop because there is much less air volume to expand.

The other factor that needs to be considered is high heat capacity of the water and the amount of time it takes to bring up that pressure. The reason those fire pistons work is because the volume of tinder is very small and they compress the air in a very short amount of time, thereby increasing the pressure and temperature very rapidly. If you try and slowly pressurize it, most of the heat generated will quickly dissapate through the walls of the chamber. You could increase the temperature of the water using the pressure/temperature principle, but the I'm guessing it would be very inefficient. It would probably be the same effect as using water to cool the heatsink fins generated from an air compressor. Water is able to absorb a tremendous amount of heat, which is why it is used in everybodys radiators.