why do some face creams seem to "bobble"?

[Dreamqueen]

I use a serum and a face cream, some combinations of cream and serum seem to "bobble' for want of a better word. If I use foundation on top it looks awful & I end up starting all over again. sometimes it seems to be ok but other times I can rub my face & it feels all bitty.

what am I doing wrong please?

Oooh, you've convinced me! Will give it a go, if it does nothing else at least there's that lovely smell to look forward to!