Forum - An European/Russian (?) cartoon scene I remember

When I was 5 on Christmas morning I remember watching an European/Russian cartoon on the TV. It had a very typical European/Russian style, im 100% certain it wasn't American or Asian.

All that I remember is that it was about a boy being naughty and because of his naughtiness (propably), a sentient black cloud followed him (?) and grew bigger for some reason, until one time he grew so fat he exploded.

That's literally all I remember, I remember seeing that scene as a kid tho.