Coat a large pot with canola oil, place 2-3 popcorn kernels and cover. Place over medium-high heat. When you hear the kernels pop, add all the remaining kernels to the pot, replace the lid, and shake periodically over the heat until all the corn is popped. When you no longer hear popping, remove from heat and transfer to a large bowl. Toss in the salt and butter (optional) and mix well. Enjoy while toasty!