What occurs when water-reactive materials come into contact with water?

Water-reactive materials can undergo a chemical reaction when they come into contact with water, often resulting in hazardous outcomes. This type of material typically reacts vigorously, leading to the potential for explosions or the release of harmful gases.

For instance, metals like sodium or potassium react with water to produce hydrogen gas and a hydroxide, which can lead to explosive reactions under certain conditions. It's important to understand that these reactions are not just passive; they often release energy rapidly, which can cause pressure buildup and explosions, making this characteristic particularly dangerous in laboratory settings.

The other options do not accurately represent the behavior of water-reactive materials, as they imply a benign reaction with water, which is contrary to the aggressive nature of these materials.