Emm, you can just have a look at any pairs chart and you will notice gaps. It is part of the game in Forex.
For some obscure pairs especially on a 1 min charts and during slow times of the day. Otherwise very rarely on the majors at any time scale on any timeframe.
Also, gaps often occur on Monday night, especially if important and serious fundamental news was released on Friday.
They can occur at weekend opening or close or during rare events such as unusual and unexpected central bank decision, "fat finger" buying or selling. For example you can see that EURUSD opened at significantly lower price at Monday last week, due to Trump comments at the weekend. This is an example of price gap in FX