Line your baking sheet with parchment paper and set aside.
Fill saucepan 2/3 full with water and bring to a boil. Once boiling, lower heat to a simmer and sit a stainless steel or glass bowl on top of the water, making sure it doesn't touch the water under it, to create a double boiler.
Pour chocolate into bowl, stirring until melted.
Remove from heat and pour melted chocolate onto a parchment paper- or Silpat-lined sheet pan. Use an offset spatula or rubber spatula to spread in a thin layer.
While chocolate is still hot and gooey, sprinkle popcorn and sea salt over the top, using as much or as little as you want.
Refrigerate until solid, about 1 hour.
Remove from refrigerator, peel off parchment paper and break bark into bite-size pieces.