"Come on," he whispered to the pipe. "Give it up."
A small sound. Like a twig snapping in a distant forest. Then, a groan.
Use only low heat (hair dryer on low or warm towels). High heat softens plastic and deforms joints.
Ice forming on exposed sections of the pipe in basements or crawl spaces. Step-by-Step: How to Unfreeze Drain Pipes Method 1: The Hot Water & Salt "Slurry"
Water moves "like molasses" or stops completely.