You will need:
2 quarts popped popcorn
1 cup packed brown sugar
1/3 cup water
1/3 cup dark corn syrup (or light corn syrup)
1/4 cup butter
1/2 teaspoon salt
1 teaspoon vanilla extract
Place popped popcorn in a large bowl; set aside.
In a heavy saucepan, combine brown sugar, water, corn syrup, butter and salt. Bring to a boil over medium heat, stirring constantly.
Continue cooking, without stirring, until a candy thermometer reads 270 degrees F (132 degrees C)
Remove from the heat; stir in vanilla.
Pour over popcorn; stir until evenly coated. When cool enough to handle, quickly shape into balls.
I poured the caramel over the popcorn while it was still in the bowl. I stirred with two large spoons.
Then I dumped the bowl onto a cookie sheet and spread the popcorn out. You do have to do this very quickly.
It is hot, so please be careful. Use silicone oven mitts, gloves or anything to protect your hands if the heat is too much. The carmel is like lava. Delicious yummy painful lava.