What you do depends on what you are using to slice. In Cura there is an option to move away form the print until "minimum layer time" is met. The problem is that your layer time is too short so the previously laid plastic is not cooling enough for the next layer. You will have some slicer options to try to cope with it so try that first. If that doesn't help then you need to add a cooling fan to the machine to blow air directly onto the newly laid plastic.