The sound of french fries, onions, eggs etc. in the frying pan is called τσιτσίρισμα, which comes as a bit of a shock for me, since I've always called it (and have always heard the people around me call it) τσιρτσίρισμα…
Don't know if this does the trick for you… With a little bit of casual liberty, you could use it in reference to, say, an effervescent vitamin or something, I guess: Σιγοτσιτσίριζε ο ηλεκτρολύτης στο ποτήρι…