Put a medium size bowl on the stove over medium heat with some oil in it. Add in the corn kernels and wait for all to start heating for 4 to 5 minutes.
Once the first corn kernel pops, cover the pot with a lid and let the rest pop (it will happen fast).
Take out of the heat once they have all popped so they do not burn.
Put the popcorn in a bowl to then cover them with the caramel.
For the caramel and to assemble:
Preheat the oven to 375º F (180º C). Line a baking sheet of about 17 x 13 inches (45 x 33 cm) with parchment paper.
Put a pan over medium heat on the stove. Put the butter there and let it melt.
Add in the sugar and salt and mix until well integrated. Once it starts to form bubbles, let it cook for 4 minutes stiring non stop.
Take the pan out of the heat, add in the vanilla and baking soda and stir using a rubber spatula.
Quickly pour the caramel over the popcorn and mix using the same spatula until all of them are coated.
Put the popcorn on the baking sheet and spread them evenly. Bake for 30 minutes until they are crunchy (it is important to stir them a little every 10 minutes for them to properly cook.).
Take out of the oven and let it cool down. They will last crunchy for up to 2 weeks.