Summarize:

Dump in 1 tablespoon (14.3 grams) of salt for every cup (250 milliliters) of water you use. Make sure the caramel is completely submerged under water. Do not dump the water out beforehand, no matter how murky or dingy it may look. By now, the salt should have weakened the stuck-on caramel, causing it to lift off the sides of the pot as soon as the water heats up. Gently scrub the sides of the pot with a dish sponge. Any remaining caramel should lift off without much difficulty. Use running water to remove any residual flakes of caramel.
Fill an enamel pot or pan with salt water. Allow the salt water to sit in the pot overnight. Boil the salt water inside the pot the following day. Dump the water. Rinse the pot.