How to prevent sweet thick glaze/sauce from setting after cooling? I attempted to make a sweet balsamic glaze/sauce from a simple recipe that called for 1 cup balsamic vinegar and half a cup of brown sugar. To my own tastes I added a bit of Worcestershire sauce, a splash of soy sauce and a little bit of rosemary. I may have added a bit too much sugar, I was doing rough measurements.

Regardless, I cooked the mixture for about 8 minutes on high heat until the syrup coated the back of a spoon.

The issue is that after the glaze was done, as it cooled, it entirely set. It ended up being more like a soft caramel, sticking to your teeth.

Did I add too much sugar? Or did I cook the mixture too hot or too long?
until the syrup coated the back of a spoon 


Then you made syrup, and that's why it had the texture of syrup. You should not have cooked it, just warmed until it dissolved, if you wanted a sauce texture. 

If the directions in the recipe are for cooking until it gets so thick, then the recipe intends the sticky texture, and you might want to use a different recipe. Or maybe they intended the thinnest possible syrup at say 102 C boiling point, and you misunderstood the vague suggestion of "coat the back of the spoon" and let it climb up to maybe 106 or 108. 

In candymaking, the ratio of the sugar to liquid is not important, because you just boil the mixture until enough liquid has evaporated to get to the right stopping point (the one which corresponds to the desired texture after setting). It only has an influence on the time of preparation, not on the final result. If you would prefer a dissolved version (not heated until you get a syrup), then the ratio becomes important.