Cold drink

Phase diagram of water with the trajectory of the liquid in our water bottle, mapped out in $P-V$ space. (Credit: Modified from image of Prof Henry Greenside)

Assume that you start in the liquid phase ( Start in the diagram). Initially, the pressure is going to drop substantially, bringing you into the vapor regime (light green).

Once it's vaporized, water will cool much faster than when it is a liquid. That's going to drop the temperature of the water to well below 200 K. No matter the pressure of space, the water will terminate as a solid of fine ice crystals as its temperature equilibrates with the temperature of the space vacuum ( End in the diagram).

Anecdotally, astronauts have said that this process is quite beautiful. Describing one such instance where liquid urine was exposed to the vacuum of space, astronaut Russell Schweickart said:

"Well, actually, in Skylab we did something similar to that. But on Apollo the urine then would go outside, and you'd have to heat the nozzle because, of course, it instantly flashes into ice crystals. And, in fact, I told Stewart this, the most beautiful sight in orbit, or one of the most beautiful sights, is a urine dump at sunset, because as the stuff comes out and as it hits the exit nozzle it instantly flashes into ten million little ice crystals which go out almost in a hemisphere, because, you know, you're exiting into essentially a perfect vacuum, and so the stuff goes in every direction, and all radially out from the spacecraft at relatively high velocity. It's surprising, and it's an incredible stream of... just a spray of sparklers almost. It's really a spectacular sight. At any rate that's the urine system on Apollo."