Drop 3 kernels of popping corn into the oil in a large heavy-bottomed, lidded pot over medium-high heat. Close the lid and wait until you hear three pops.
Quickly add the remaining popping corn and sprinkle with the sugar. Close the lid once again and, wearing oven mitts, give it a good shake.
Cook, shaking the pot regularly, until there are more than a few seconds between pops. Remove from heat and leave the lid on until popping stops completely.
Sprinkle with salt and stir with a big spoon. Be careful, as you are dealing with very hot sugar. Allow to cool 5–10 minutes before serving.
Notes
Test with 3 kernels: When those three pop, the oil is hot enough to add the rest.Sugar burns fast: Keep the pot moving once the sugar goes in so it caramelizes evenly instead of scorching.Hot sugar caution: The melted sugar is very hot — use oven mitts and let it cool before tasting.Shake, shake, shake: Constant shaking keeps the kernels and sugar from sticking and burning.