Preheat a thick pot over medium heat and add vegetable oil.

Reduce to medium-low heat, add popcorn kernels and a piece of butter.

Once the butter melts and bubbles appear around the kernels, cover the pot with a lid.

When popping sounds slow down, remove the lid and transfer the popcorn to a tray to cool.

To make caramel sauce, add sugar and water to a pot and heat over medium-low heat without stirring.

Once the syrup starts bubbling, add butter and stir until well combined.

When the caramel sauce thickens and flows smoothly, turn off the heat.

Quickly mix the warm caramel sauce with the popcorn using two spatulas.