When you find your brown sugar in a brick-like mound, blame improper storage. When brown sugar is exposed to air, the moisture in the sugar evaporates. If you need to use the sugar immediately, measure out how much you'll need and place it in a microwave-safe container with a damp (not dripping) paper towel. Microwave in 30-second intervals until softened. Make sure you store brown sugar in an airtight container in a cool, dry place (but not in the refrigerator).