It is hard to predict what might happen when demons leave a person during deliverance ministry. Sometimes they leave while giving no indication of their departure. Others will depart while the person yawns, coughs or has other mild responses. In rarer cases, there will be more severe responses like crying out, shaking or convulsing.
In the Gospels and Acts we see eighteen confrontations with demons, most of which contain no mention of any manifestations when the demons left. In four others, we see manifestations when the demons were forced to leave.
The most common manifestation noted is screams or shrieks – see Mark 1:26; Luke 4:41; Mark 9:26. The other reaction is a forceful shaking or convulsing, even throwing a person violently to the ground – see Mark 1:26, 9:26.
There is one episode where the demon group called Legion left a man and manifested in a herd of pigs (Mark 5:1-20), but since the Gospel accounts make no mention of the man himself being affected when the demons left, for our purposes we will take no further note of it.
So to sum up, of the 18 episodes in Scripture, only about 1/5 of them noted any manifestations. It is clear that demons can manifest when they leave (sometimes violently), but in most cases the episodes recorded showed no manifestations. This mirrors our own ministry experience. If manifestations are troubling or distracting, you can shut them down by binding and silencing the demons in the name of Jesus.