Heat 2 tablespoons vegetable oil in a very large pot over medium-high heat. Put 4 popcorn kernels into the oil and cover until popped; add remaining kernels to the saucepan in an even layer. Cover and remove from heat, about 30 seconds. Return to heat and gently shake pan back and forth over the burner until popping slows to several seconds between pops, 1 to 2 minutes.

Divide popcorn among large bowls and set aside.

Combine brown sugar, corn syrup, coconut oil, and salt in a sturdy pot over medium-high heat. Cook, stirring occasionally, until the mixture reads 270°F (132°C) on a candy thermometer. Add condensed milk, mix well, and heat back up to 270°F (132°C). Remove from heat and let cool for 1 minute. Mix in vanilla extract.