When we observe something out of the ordinary or a peculiar happening, we often use the phrase "notice a curious fact." However, there are various other phrases and synonyms that convey the same meaning. For instance, we could say "a surprising discovery" to indicate an unexpected find. Alternatively, "an interesting observation" would convey a sense of intrigue or fascination. Furthermore, "a peculiar occurrence" or "an unusual happening" would reflect an unusual or strange situation. Lastly, we could use "a noteworthy detail" or "an intriguing tidbit" to emphasize the importance or interest of the fact observed. In summary, these synonyms provide an array of alternatives for describing a curious fact.