Pour the apple cider into a 6 quart non-reactive stockpot or dutch oven. (Don't use aluminum or copper.) Mark the depth of the cider on a wooden skewer.

Bring the cider to a boil and cook for about half an hour.

Pour the cider through a cheesecloth-lined fine mesh strainer to remove the pectin.

Clean the pot and return the filtered cider to the pot.

Return the cider to a boil and then turn the heat down to medium/low.

Simmer the cider for 4 to 6 hours, until it's reached 1/7th it's original volume (as measured on a wooden skewer). Alternately use an instant-read thermometer. The finish temperature is 225 degrees at sea level, and drops by 1 degree for every 500 feet in elevation rise.