Why does my kitten do this?

i have a kitten that is extremely affectionate. she purrs like crazy and kneads all the time. she always wants to be very close to me which i do not mind, i am 8 months pregnant so she loves to cuddle up at the top of my stomach to rest or sleep but there are times that she will get right up in my face and open her mouth like she is trying to meow and spit will shoot out. it is like when a person can lift it's tounge and spit shoots out, its almost like that is what happens to her. sometimes she will do it when she is laying down kneading and it will spray my arm. its really wierd....