WEST STYLE COBB UNEXPECTEDLY

out of the blue means suddenly unexpectedly but  it's such a nice way of saying it out of the blue  

With Hangouts, friends can drop by unexpectedly -- it's like bumping into someone you know

'Run' can be used when we need to go somewhere unexpectedly for a short time.

These experiments brought him to his formalum or in-paintings, in which he continued to examine the relation between representation and abstraction. What started as a representational painting was being reworked in such a manner, the imagery was entirely obliterated, using gestural brushstrokes and thick impastos. Uniquely, Richter made these gestural brushstrokes without being expressive, pulling the paint across the canvas in an emotionless manner, involving expression as an impelling force of painting. Doing so, Richter emphasised the painterly gesture, a witness of Richter's engagement towards the abstract as a counter-model of the figurative, coming to terms with the new possibilities for painting offered by abstraction and minimalism. Furthermore, from a personal perspective, the 1970s were not the happiest of years for Gerhard Richter, as his marriage with Emma was gradually coming to an end, and he lost his very dear friend Blinke Palermo unexpectedly in 1976. As a result, his grey paintings, but also his figurative works, think of his seascapes in particular, are embedded with a deep melancholy.

unexpectedly lead to the creation of the Red Army  and the start of the civil war between Communists  

And third, “drop” occurs regularly as a verb,  meaning, to fall unexpectedly or suddenly.  

things come up means that some situations happen unexpectedly.

So this didn't arise unexpectedly.

This leaves them much more exposed if the economy unexpectedly gets worse again and could get them into deeper trouble with their finances.

turned into awe when their camera showed them that the boulder was unexpectedly covered