Pop popcorn and set aside. Place brown sugar, Karo syrup, salt, and butter in a microwave safe dish. Microwave for 30 seconds. That should be enough to melt the butter at least half way. Stir it all to combine. No microwave on high for 2 minutes. Take it out and stir. Microwave for 2 more minutes.

While the caramel is cooking, put the popcorn in a big bowl. Use one that is way bigger than you think you’ll need.  Also, remove any un-popped kernels.  When the caramel is done cooking, take out of microwave and add baking soda and vanilla.  Stir well and then pour over popcorn and stir up popcorn immediately to coat.

Eat warm straight out of the bowl, or spread out onto waxed paper or foil and let cool to room temperature (for soft, gooey popcorn).

For crunchy caramel corn: spread out on a cookie sheet (you might need 2) and bake at 300 degrees for about 20-30 minutes, stirring every 10-15 minutes.  Pull out a piece and pop it in the fridge to let it cool quickly to test crunchiness!