If popcorn came out bad when popped in coconut oil, then yeah you did something wrong or somehow bought the wrong thing.
Get extra virgin coconut oil and it will have a certified organic symbol on it. I use it for everything except in tomato based sauces and breads, where I continue to use olive oil. It is not typically on the cooking oil aisle... but in the natural foods aisle or section. Or on Amazon.com or elsewhere online. Nutiva is a good brand.