Dairy free popping candy?
Unfortunately, I don't think so.

Milk sugars show up in the regular pop rocks ingredients list, and I also looked at the ingredients list for the culinary grade unflavored popping crystals, but those still contain milk sugars - it isn't just in the extra flavorings, but in the base material recipe.  And as far as I know, there's no real way to make this popping candy at home. 

You can look up the homemade carbonated candy recipes that use citric acid and baking soda, but those tend to be fizzing, not popping, when activated.  It may be close enough for your purposes, and the recipe doesn't have milk in it, but names aside it is not the same candy.