Your cat may throw up occasionally in order to eliminate hairballs or from eating too rapidly due to competition around the food bowl. There could also be a more obvious explanation. If your kitty frequently gags or vomits after dinner, she may simply be chowing down too quickly. In fact, one of the most common reasons why cats vomit is that they eat too fast.
When cats eat too voraciously, they often swallow their kibble whole and end up gagging on it. The easiest way to slow down an overeager feline eater is to feed a larger kibble size so she has to take longer to chew and swallow. You can also try feeding your cat smaller portions of food more often.