If the freezing temperature is kept about -6 C then the initially-hot water is most likely to (apparently) freeze first.
(the freezing temperature; is kept; ) (the initially-hot water; is; most likely to (apparently) freeze first; T:then) (the initially-hot water; to apparently freeze; T:first)
the freezing temperature the initially-hot water the initially-hot water
is kept is to apparently freeze
most likely to (apparently) freeze first T:then
T:first