You are bent over the sink, with your mouth open, so you don't swallow. Most will run out right away, the rest you can get out by blowing your nose.
If you use a hydro floss machine like I do, the solution also gets into the sinus cavities. Tilting your head from side to side will cause more solution to come out.
Sometimes after you are done, and are busy doing something else by bending over, more solution will start to come out. This is good, as the solution has had time to be in there longer.