Pop the popcorn. This may take more than one round, depending on how you make it. Place popped popcorn in a roasting pan and put aside. You may need two pans to make stirring easier.
Preheat oven to 250 degrees F.
Make the caramel. Melt butter in a saucepan over medium heat, then add brown sugar, corn syrup, and salt. Stir constantly until this mixture comes to a boil.
Allow mixture to boil for 4 minutes without stirring.
Remove from heat and add in baking soda and vanilla extract. Stir well, then pour over the popcorn. Stir the popcorn well to start coating. Coating will not be complete at this stage.
Place popcorn in oven and bake for one hour. Remove from oven every 15 minutes and give the popcorn a good stir. This will help coat the popcorn more evenly.
Remove from oven and allow popcorn to cool. Break up the large chunks of caramel popcorn when it is cool.
Spread the caramel popcorn out in a single layer on a baking sheet covered in parchment paper.
Melt the white chocolate with 1 tsp of coconut oil in a bowl. Use the microwave in 30 second increments, stirring between rounds. Drizzle melted white chocolate across the caramel popcorn using a spoon.
Melt the dark chocolate with 1 tsp of coconut oil in a bowl. Use the microwave in 30 second increments, stirring between rounds. Drizzle melted dark chocolate across the caramel popcorn using a spoon.
Allow chocolate to solidify. You can speed this up with about 30 minutes in the refrigerator, but do not store the popcorn in the fridge. Move into a serving bowl or storage container when the chocolate is solid.