Combine the sugar, butter, corn syrup and salt in a saucepan and bring to a boil, stirring occasionally. Once it begins to boil, stop stirring for 5 minutes, or until mixture reaches 255 degrees on candy thermometer. (You may have to adjust according to altitude and humidity). Remove from heat and stir in baking soda. The mixture will start to foam, so stir well until blended.
While the caramel mixture is cooking, pop the pop-corn either in a hot air popper or microwave. Once you have popped the pop-corn, remove any unpopped kernels. Now place the popcorn in a large (buttered) metal bowl. Pour the hot mixture over the pop-corn and toss gently with well buttered forks to distribute evenly. Spread onto 2 ungreased baking sheets and bake at 200 degrees for 1 hour, stirring every 15 minutes. if it starts to look too golden it may be time to take it out!
*Oven temperatures vary not only with model but with altitude, so you'll have to adjust time accordingly.
STORAGE & SERVING
Remove the caramel corm from the oven and allow to cool completely. Once cool, break it into clusters, and store in a tightly covered container. For a Halloween party, serve in decorative bowls. For treats, fill those little paper Halloween bags and tie off with black ribbon to hand out.
14 cups popped popcorn
1 cup butter
1 teaspoon salt
2 cups sugar (packed)
1/2 cup light corn syrup
1 teaspoon baking soda