Hominin encephalisation is a combination of processes: an underlying gradual trend towards larger brains is punctuated by several large step increases at ∼ 100 Ka and ∼ 1.9 Ma [3]. (journals.plos.org)
Luckily, in regards to the difficulty level behind The Witch and The Hundred Knight, there is a constant and gradual trend in terms of amount of challenge being thrown in. (jgghgames.com)
In the case of the SST datasets analysed by Thompson et al. it looks to me that natural variability (volcanic influences, ENSO etc.) have conspired to make a relatively gradual trend look like a sudden one. (julesandjames.blogspot.ru)