This occurs when liquids are heated very rapidly and no nucleation occurs, thus when the liquid finally boils, a large vapor bubble is formed that pushes the liquid out of the test tube. This expulsion of boiling liquid poses a serious hazard to others and oneself in the lab.
Boiling chips alone may not prevent bumping and for this reason it is advisable to boil liquids in a boiling tube. In addition, test tubes should always be pointed away from oneself while boiling, just in case bumping does occur.
A sealed capillary tube can also be placed in a boiling solution to provide a nucleation site, reducing the bumping risk and allowing its easy removal from a system.
- "Proper Heating of Test Tubes". CR Scientific LLC. Retrieved 30 October 2010.
- Beran, Jo (1 November 2010). Laboratory Manual for Principles of General Chemistry. John Wiley and Sons. p. 25. ISBN 0-470-64789-2.