Is Choking and being sick with a puree normal?

Ok i know its normal for them to gag and such with lumps but how normal is it for a baby to do this with purees. Gagging and being sick when eating a puree but he can eat cheerios and bits of bananas and bits of other things but if you put puree in his mouth it makes him choke? Is it normal? And im talking every bite here not just the first he chokes on them all and hes just over 7 months and been having them for a month and a bit.