Use the microwave to soften a solid lump of brown sugar. Keep the sugar in its plastic packaging, or place it in a zip-top plastic bag. Add a few drops of water, then heat on medium power for 10 to 20 seconds, repeating as needed. No plastic bag? No problem! You can also place the lump of hard sugar in a microwave-safe bowl with a damp paper towel on top. Heat on high at 15-second intervals until the sugar is soft and loose.