The simplest way would be to evaporate the water.
One way to go about that would be to pour your 2 litres of water in a small high-sided container and then fit a plastic bag over it. Duct tape the bag so it fits tightly round the container.
You should use a long thin bag, so that the bag still has some space left in the end.
Get a vacuum cleaner.
Tape the other end of the bag round the end of the vacuum cleaner hose.
Stand your container on the floor and put the vacuum cleaner on the table
You want to arrange it so that the suction is in a vertical line from your container and that the end of the vacuum hose does not dip into the water.
Turn on the vacuum at low suction.
Leave it running.
Make your room hot.
The water should evaporate in an hour or two depending on how warm your room is.
By the way I've never tried this with a vacuum cleaner and this is kind of experimental. I've only ever done it with lab equipment, the principle is the same though.
The advantage is you don't have to heat the solution.