I have just finished GSOC 2018 contributing to Boost.uBLAS. I agree with Adam.
There is no Boost GSOC 2019 Wiki yet. However, you could start reading https://github.com/boostorg/boost/wiki/Boost-Google-Summer-of-Code-2018 and https://google.github.io/gsocguides/student/ in order to understand the requirements for being accepted and the process. Also have a look at https://github.com/BoostGSoC18 how previous GSOC students have implemented their projects and organized themselves. I think there will be something similar for GSOC 2019.
In addition to this you can also visit boost organization on GSoC site[1]. Here you can find Code submision links. This links will be helpful because all the students have written blogs about what they have done and what can be done in future it will make things easy for you to understand and
On Wed, Aug 29, 2018 at 10:00 PM Cem Bassoy via Boost