From what I understand, Google often does a bit of both testing through live traffic and evaluating the trustworthiness of pages before giving them a boost in rankings. In fact, Google is known to give new or recently updated pages exposure for a limited time to monitor their performance against existing results. Shifting up and down within a short period of time is, in fact, quite a normal scenario and doesn't always indicate a problem.
Yet, the true signal lies in the subsequent behavior. A page that continuously resurface, measures higher impressions from a wider range of keywords, or after each change, it is gradually gaining ground again, these situations normally indicate that trust is being established. Then again, if there is only a one-time surge and then the disappearance of a page, the most common explanation is that it suffers from a lack of sufficient long-term factors, like poor intent match, thin topical coverage, weak internal linking, or limited authority.