Well...I think they go somewhere where all the cats can chat about their combos, sushi, podiums, etc. Then they go back to the dance floor for the new round! ^^

You can discuss here of what you think when cats turn to bubbles and disappear.
Yup. Anything that you think.

The bubbles go to factories they pop em' and the cat remains go back to turn back into a nekodancer and then there is a new round

They are teleported to the bench until next round and bubbles pop

Maybe those bubbles are the cat's spirits and they float up in the air and the rhythmic cat god tells them politely not to fail again.

Next round, the usual.

they evapourate into the clouds...

they turned into invisible carrots then next round they turned back into cats

They go to StarClan and are reincarned for the next round

They fall into some kind of black hole where they do chatting and chatting and they fly to the dance floor for next round

THEY. GO. to sleep.

they turn into sushi and then turn back into catz :D

They derp around

they go to heaven and then come back down to earth

Perhaps the bubbles pop, then the cats chat around for a bit then get teleported to the next round.

they just go have a poop/shit in the invisible toilet in heaven

they go play OpenITG

They go to a green waiting room, the one who died first needs to stand in the corner and thinks about his/her life :D

The bubbles go to heaven and then the cat just waits there till' the next round, and is turned back into a live cat.

The kitties go to a star called Sidelines, which is like an audience for the remaining cats. Or they go to Starclan XD

maybe so they dont show that they are dead? just a guess

they are teleported to a litter box so they can poop
then they are bought back next round