There are hundreds of impatience varieties but the exploding seed pods are on plants  with ripe seeds so that would mean early blooming varieties and the more wild or species impatience. The newer varieties are bred to flower continuously with less ripening seeds. Impatiens grown in the sun will also be more likely to have ripe seed pods and that exploding feature. The one warning is that when those seeds explode the plants can become invasive. So now many gardeners prefer the less seedy plants.  Keep growing, Marianne Binetti