Now let's get back to that one gallon of sap. If you boil down one gallon and end up with 2/3 of a cup you run the great risk of burning the syrup to the bottom of the pot. It's best to have at least three gallons to boil down to syrup. When I only have a little bit of sap, I only boil it down partway. It's not syrup at that point, but has genrally taken on an amber color and tastes pretty sweet already. I let that cool, pour it off into a Mason jar and stick it in the refrigerator. The next time I boil sap down, I add this too it. This way enough is in the pot so that it can be boiled to syrup stage without being so little that it burns to the bottom of the pot.