@Jake-Parker you can rewet those old tubes by adding a little bit of water and gum arabic. That's another reason I love watercolor. Just cut open the tube and put the powedered remains on a plastic palette, then mix the mixture in.
PS: for others out there wanting to try watercolor, not all of them are made equally in terms of re-wetability. Windsor Newton colors will NOT rewet back to their tube strength. I use M. Graham paints for sketching because they can always be sprayed with water and become totally workable again. Schminke paints will also re-wet easily.