Chop the chocolate into small pieces and place it in a medium heat-safe bowl. Place the cream in a small saucepan over medium heat and bring it to a simmer.
Pour the hot cream over the chocolate and allow it to soften the chocolate for a minute. Use a whisk to blend the cream and chocolate together. Stir until you have a smooth, homogenous mixture. Press a piece of plastic wrap on top of the ganache and refrigerate it until it is firm enough to scoop, about 3 hours.
Scoop the ganache mixture into small balls, about 3/4" in diameter, and roll them into circles between your palms. If the ganache starts to melt and stick, use a little cocoa powder on your palms to prevent sticking.
Once they're rolled into balls, open 4 of the Pop Rocks envelopes and pour them into a small bowl. (Do not open them early, as the humidity in the air will start to make them sticky once the package is opened.) Roll a truffle ball in the Pop Rocks, then roll it briefly between your palms to embed the candy into the ganache. If the rocks don't stick, briefly roll the truffle between your palms to soften the chocolate, then roll it in Pop Rocks.
Set the coated truffles on a baking sheet covered with aluminum foil, and repeat with remaining truffles and Pop Rocks. At this point you want to dip the truffles as quickly as possible, to avoid exposing the Pop Rocks to air for an extended amount of time. However, the ganache might be a bit too soft for dipping, so I recommend putting the truffles in the freezer while preparing the dipping chocolate.
You don't want to freeze them, just chill them quickly for about 5-10 minutes. If you do not plan on dipping them immediately, do not put them in the freezer, just wrap them well with cling-wrap and refrigerate until you dip them.
While the truffles chill in the freezer, place the coating chocolate in a microwave-safe bowl and microwave until melted, stirring every 30 seconds to prevent overheating.
Once the coating chocolate is smooth and the truffles are firm enough to dip, it's time to dip the truffles. Use dipping tools or a fork to submerge a truffle in the chocolate. Remove it from the chocolate and tap the fork against the bowl several times to remove excess chocolate. Replace it on the foil-lined baking sheet, and, while the chocolate is still wet, sprinkle popping candy from the remaining envelope on top. Repeat with remaining truffles and chocolate.
Allow the chocolate to set in the refrigerator for 10-15 minutes. Store Exploding Truffles in an airtight container in the refrigerator, but for best taste and texture, serve at room temperature. Because the popping candy does absorb moisture, these are best eaten within 24 hours of making them, although they will still pop up to 3 days later.