Not a chemist but I think it's simple, the moisture that keeps the glue fluid is sucked out into the baking soda. I assume it's probably purified water or alcohol. Water is coherent, it sticks to itself so it'll suck all of the water out of the glue. If Alcohol (or acetone) that stuff dries pretty quick so adding a super dry component that is happy to pull the liquid out will make it work quickly. What interests me is the strength factor, if it is in fact a stronger bond, it probably has to do with the size of the molecules in the glue and in the powder, they basically become a crystalline structure. Makes sense.