Add the soy sauce, sugar, and water to a medium or small saucepan. Stir occasionally as it comes to a boil to prevent sugar from burning, about once a minute. Once it starts bubbling, reduce the heat to medium-low or low. Simmer, uncovered, until the sauce thickens a bit (small bubbles and frothing are okay, you just don't want lots of big bubbles, or it can quickly bubble over).

Once it starts to thicken, start stirring frequently. And once it almost reaches a thin syrupy consistency, about 10 minutes in, add the molasses. Stir frequently and continue cooking for another 5 minutes, until it has thickened to a maple syrup consistency.

Take off the heat. Carefully pour into a heat-proof jar. Once cooled to room temp, (it will thicken a fair amount as it cools), seal the jar and store in the fridge for several months.