Alright Dave here it is.
Im guessing your talking corn and potatoes and things of the sort. What you wanna do is boil the potatoes until they are soft enough to fall off of a serated edge knife when you stab 'em. And the Corn is done when it is soft enough to eat.
I like to put all of my seasoning in the water before and let it boil adding a stick or two of butter and lemon juice, stirring a little bit to help it dissolve. Once that's done and your water is at a rolling boil drop in your crawfish. The water should stop boiling as you said. When the water returns to a boil turn off your gas. I like to let them sit in the water for another 10-15 minutes to let them soak up some more seasoning. Then take them out and throw 'em in an ice-chest. What welike to do is serve them in platters giving each person two platters one full of crawfish and one empty to throw the heads in.
What you can also do is just put your liquid crab boil and a litte bit of extra seasoning in the pot and do everything else the same, except dont let them sit as long. When you put 'em in the ice-chest sprinkle seasoning, lemon juice, and butter on 'em( I like to use the butter in squeeze bottles for this because it melts faster) and then let them steam in the ice-chest for a while after that.
The lemon juice and butter make them a little bit easier to peel.
There it is. Hope that's what you were looking for.
Chuck Norris bites the hand that feeds him,and eats their entrails.