What to do with leftover Tomato Sauce/Paste

If I make soups, stews, I never use the entire can of tomato sauce/paste and I hate to throw away the leftovers.  In the past I would just pour it in a sandwich bag and freeze it but when I would try to use it and have to peel the bag out from the crevices of the frozen sauce and  it was just kind of annoying really.  Trying to break a chunk of didn't work very well either.   I read over on