The word "popping up" can be replaced by numerous synonyms depending on the context. Some of the commonly used synonyms for this phrase include appearing, emerging, arriving, springing up, materializing, surfacing, coming into view, and becoming visible. These terms can be used to describe various scenarios, such as new ideas or trends that are emerging, events or incidents that are occurring suddenly, or objects that are becoming visible or noticeable. Using synonyms can help to add variety and depth to your written or spoken communication, and also allows you to better convey the meaning you intend to express.