Preheat the oven to 250 degrees Fahrenheit and line two baking sheets with parchment paper.
Make your popcorn. Add your coconut oil to a large pot or dutch oven and melt over medium heat. Add 3 popcorn kernels and place the lid over the pan. Once they pop, the oil is ready. Add the remaining popcorn kernels, spreading out evenly over the bottom of the pan in a single layer. Cover with a lid and allow kernels to pop. Shake/agitate the pan around a few times while it pops to make sure all the kernels get popped. Once done, pick out any kernels that didn't pop (you can do this by transferring the popcorn to a large bowl or baking sheet).
Make your caramel sauce. Wipe out your pan and let cool for a minute or two. Melt your butter over medium-low heat. Add your coconut sugar and full-fat coconut milk and whisk well to combine. Cook for 5-7 minutes over a low simmer, whisking constantly. Be careful not to burn it and turn down the heat if needed. You can also remove it from the heat for short periods of time to make sure it doesn’t get too hot. As it cooks, the sauce will thicken. Remove from heat and let cool a little (it will thicken a little more). Stir in the salt.
Coat popcorn in caramel sauce. Add your popcorn to the saucepan the caramel sauce is in. Using a spatula, carefully mix well to combine, making sure to evenly coat all the pieces. Pour the mixture out on your lined baking sheets, spreading out in a single layer. The more spread out it is, the crispier it will get. If there is extra caramel sauce in the pan, use a spatula to drizzle it over the popcorn.
Bake for 30-35 minutes, stirring once halfway through.
Enjoy! Enjoy it warm or let cool completely before storing or transferring it. As it cools, it will crisp up more.