Final answer:
When heating a liquid in a test tube, always point it away from people and use a boiling chip or stirring rod to prevent bumping. Handle hot glassware with protective equipment to avoid burns.
Step-by-step explanation:
When heating a liquid in a test tube, it is important to follow safety precautions to prevent accidents such as burns or chemical exposure. First, never point the open end of a test tube toward yourself or others to avoid the risk of the contents being expelled towards anyone; this is referred to as "bumping". Instead, angle the test tube away from all individuals. Use a boiling chip or stirring rod in the test tube to prevent superheating, which can cause sudden boiling. Superheating occurs when a liquid's temperature exceeds its boiling point without actually boiling, which can lead to a violent eruption of the liquid when the superheated zone collapses. Always handle hot glassware, such as beakers or test tubes, with appropriate protective equipment, like tongs or heat-resistant gloves, to prevent burns.