Getting baby to eat solids?

My son is 8 months old. Our pediatrician didn’t let us start his on purées until he was 6 months old. I’m not sure why, he didn’t give us a reason, but we listened because he’s the doctor & this is our first child. He does great with purées, & has since we started him on them. He’s a great eater. But now, he’s mastered the pincer grab & chewing, so we tried giving him the little puff things. He chewed it fine (besides, it was in his mouth long enough to dissolve), but then he started gagging & he eventually projectile vomited. I know it’s time to start upgrading his food, he seems ready. But is there something we can do to help him not throw up?