Sounds a little like Fizzies over here. They were tablets that fizzed out a fruits flavored drink in water. Kids would dare each other to stick these in their mouths.Here in Poland, we have this stuff, which you would call orangeade in English. It comes in three colors, and it's literally just fizzy sugar water. You could call it a poor man's Irn Bru, since it's about as trashy as that, but less unique in taste.
Also, there is a very popular version of this, which was very popular back in communist times. It's essentially a powder you mix with water, kinda like Kool-Aid in America. But kids preferred to eat it out of the packet, because it was more fun, with the fizz on your tongue and stuff. You can still get it today in various flavors.