In a large lidded sauté pan, melt the butter with the maple syrup and the salt over a medium-high heat. Once foaming, add the popcorn kernels and shake to coat evenly in the butter mixture. Cover and cook for 5-8 minutes. After a few minutes you should start to hear the kernels pop – keep shaking the pan every so often and cook until there are only a few pops. Remove the lid and stir the popcorn to coat it in the caramelised butter (don’t worry if there are unpopped kernels). Tip into a bowl, taste and season with more salt if necessary. Eat as soon as you can put it in your mouth without burning yourself.