I found a bottle of sherry and thought it had a strong fig taste so I tried reducing it with maple syrup. In practice this meant I just brought it to a boil uncovered and waited until maybe a quarter was left. It ended up being tart and somewhat darkly fruity with a maple sweetness. Not terrible for a first attempt at using it, but this made me wonder: what is the difference between reducing this by boiling and reducing it by a long, slow simmer? I don't imagine they're equivalent. My instinct is that gentler heat better preserves nuances of flavor but I'm really just guessing.